Collet pads



1960 F. H. SMITH 24,903

COLLET PADS Original Filed May ll 1955 3 Sheets-Sheet 1 L V Y It 6. 4. flfDE K h- JM/ 7.

INVENTOR.

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A TTOENEY.

1960 F. H. SMITH Re. 24,903

' COLLET PADS Original Filed llay ll, 1955 5 Sheets-Sheet 2 f'TiEDEk/CK H. in;

INVENTOR.

A TTOENE Y- F. H. SMITH COLLET PADS Dec. 6, 1960 Original Filed May 11, 1955 3 Sheets-Sheet 5 6. mm 2 Wm MV 6 Jw. A H m E M E m Maw.

ATT'OENEY.

United States Patent Ofi ice COLLET PADS Frederick H. Smith, 3567 Stop Eight Road, Dayton, Ohio Original No. 2,883,200, dated Apr. 21, 1959, Ser. No. 507,564, May 11, 1955. Application for reissue Sept. 24, 1959, Ser. No. 842,550

8 Claims. (Cl. 279-58) Matter enclosed in heavy brackets appears in the original. patent but forms no part of this reissue specification; matter printed in italics indicates the additions made by reissue.

The invention relates to collets which are used in connection with automatic screw machines and turret lathes, and through which stock is advanced and is gripped by collet pads in the machining process of the stock.

The present invention relates to collet pads and to the construction thereof, with the same being adapted for use without the use of master collets, in connection therewith. in the conventional collet system, the master collet is of tubular form and tempered so as to form a series engaging end portion in order that the same may be.

machined or ground to the necessary workable limits. In the annealing process, the work-engaging end becomes soft and is subject to considerable wear thereafter in the use thereof. In the use of pads with the conventional type of master collets, the pads are in the form of inserts secured in the master collets by means of screws.

It is the intent and purpose of the present invention to provide collet pads of such design and construction to replace the conventional master collets and their pads. with a more simple and economical form of collet pads.

which entirely eliminates the master collets.

The principal object of the invention therefore is the provision of collet pads eliminating the combination of master collets and their associated pad members.

A second object is the provision of collet pads which are simple of construction and which are more economical in the manufacture thereof than the conventional type master collets and their pads.

Another object is the provision of collet pads which are adapted to an unlimited variety of sizes and shapes of stock.

A further object of the invention is the provision of a collet pad construction in which the pads are provided as individual members and are tied together into a single unit.

Other particular objects and advantages of the invention will suggest themselvesin the course of the following description, and that which is new will be pointed out in the appended claims.

Thep referred and most satisfactory manner of carrying out the principles of the invention in a practical and economical manner is shown in the accompanying draw ings, in which:

Figure l is a partial elevation of the stock-working end of a machine showing the housing, the stock, the spindle nut, and the collet pads embodying the features of the invention.

Figure 2 is a side elevation of the end portion of the machine, taken from line 22 of Figure 1.

Figure 3 is a detail section through the spindle assembly, as taken on line 3'3 of Figure 2, and showing the collet pads in engaged relation with the stock.

Figure 4 is a detail section similar to that shown in Figure 3, but showing the collet pads in disengaged relation with the stock.

Figure 5 is an end elevation of the spindle assembly:

including the collet pads and the spindle nut, as taken from line 55of Figure 3.

Figure 6 is an end elevation, taken from line 66 of Figure 4.

Figure 7 is an end view of a piece of stock used in the i forming of the collet pads.

Figure 8 .is an end view of the piece of stock shown in Figure 7, but with the same having a bore formed therethrough.

Figure 9 is a side elevation, taken from line 9-9 of Figure .8.

Figure 10 is an end elevation of the stock after the same has been formed and cut oif to provide the collet pad body.

Figure 11 is an elevational view showing the configuration of the end portion of the tool used in forming the.-

body shown in Figure 10.

Figure 12 is a detail end elevation of the body after the same has been cut to provide the three pad members.

Figure 13 is a detail end elevation of the three padmembers as the same appear when brought together by means of resilient-spring rings which fit into formed grooves or channels.

Figure 14 is an elevational view of one of the resilient spring rings. used in holding the pad members in as sembled condition.

Figure 15 is a side view of the resilient spring ring shown in Figure 14.

Figure 16 is a side elevation showing the pad members held. in assembled condition by means of the spring rings.

Figure 17, 18 and 19 are side elevations of assembled pad. members, and withv each of the figures showing a modified design of the outer peripheral surface of the assemblies.

Figure 20 is an end elevation of an assembly showing the same as being formed to accept hexagonal stock.

Figure 21 is an end elevation of a pad assembly showing the same as being formed to accept square stock.

Figure 22 is an elevational view of the end portionof an automatic screw machine or a lathe in which the collet pads are adapted to be used.

Figure 23 is an end view, taken from line 23-23 of Figure 22.

Figure 24 is a detail section, taken on line 24-24 of Figure 23.

Figure 25 is a side elevation of the collet pad assembly shown in Figures 22, 23 and 24.

Figure 26 is an end elevation of the collet pad assembly shown in Figure 25.

Like characters of reference designate like. parts throughout the several views.

In order that the invention may be more fully understood and appreciated, I will now take up a detailed description thereof, in which the same will be more fully set forth.

Referring now to the drawings in detail, 30 represents the head of the machine in which spindle 31 is located, with the spindle being driven by gears (not shown) of the machine. Spindle 31 is hollow for the reception of stock 32 extending therethrough. The forward end of spindle 31 is provided with the removable sleeve 33, with the sleeve having a channel 34 formed in its side and registering with a stud 35 of the spindle 31. The sleeve has a flange 36 formed at the rear end thereof, against whichthe rear end of compression spring 37 is seated. The assembled collet pads 42 are placed in the forward Reissued Dec. 6, 1960 3 end of sleeve 33, as shown in Figures 3 and 4. The forward end of the sleeve is tapered to fit the tapered surface of the collet pads, and with the rear end of the collet pads providing a surface for engagement with the forward end of compression spring 37. After the collet pad assembly has been positioned in the forward end of sleeve 33, spindle nut 38 is threaded onto the forward end of the spindle and with the inner surface of the spindle nut being adapted to bear against and force the collet pads rearwardly in the tapered end of the sleeve. With the rearward movement of the collet pad assembly in the tapered end of the sleeve, the collet pads are forced inwardly in concentric relation and thereby. provide a gripping action around the stock 32, as shown in Figures 3 and 5. When the spindle 'nut. is loosened slightly, the movement thereof permits the compression spring to force the collet pad assembly forwardly,upon-which' movement, the colletpads expand concentrically outwardly with the gripping action of the collet pads being released from the stock 32, as shown in Figures 4 and 6, after which the stock is advanced by meansof the stock-advancing fingers (not shown) of the machine.

- The collet pads are formed from a length of stock 39 (shown in Figure 7). The stock is drilled forming the bore 40 therethrough, with the bore being of substantially the same size as the stock with which the same is to be used. After bore 40 has been formed in the stock, the outer surface of the stock is formed by means of cutting tool 41 shown in Figure 11 and with the same forming the outer periphery on the stock as shown in Figure 10. After the outer periphery has been formed as shown in Figure 10, the same is cut into segments 42 by means of a saw, as indicated in Figure 12. Figure 13 is an end view of the segments 42 in assembled relation. The segmerits are held in assembled condition by means of a pair of resilient spring rings 43 which are'positioned in' channeledgrooves 44"0f the segments, as shown in Figure 16. As clearly seen in Figures 14 and 15, the rings 43 are flat springs forming a one convolution ring. The rings 43 prevent displacement of the segments both concentrically and longitudinally with relation to each other.

'The'rearward end 45of the segments provide aseat for the forward end of compression spring 37. The beveled or tapered surface 46 of the segments are adapted to engage the tapered inner surface of the forward end of sleeve 33, while the forward faces 47 of the segments are adapted to bear against the rear surface of spindle nut 39, as more clearly shown in Figures 3 and 4.

In Figures l7, l8 and 19, I have shown outer profiles of the collet pads diiferent from that shown in Figures 3, 4, 10 and 16, but with the segments 42 comprising the same being secured against displacement by means of the springs 44.

Figure 20 shows an assembly of collet pad members having a hexagonal opening 48 formed therethrough for the reception'of hexagon-shaped stock.

Figure 21 shows an assembly of the collet pad members having a square opening 49 formed therethrough for the reception of square stock.

InFigure 22 numeral 50 designates the head of the automatic screw machine or the lathe while 51 designates the stationary tapered sleeve member of the machine and with the sleeve having a taper 52 formed therein and with threads 53 being formed thereon for the reception of the collet chuck nut 54. It will be noted that the collet chuck nut 54 has a tapered aperture formed therein for engagement with the collet pad assembly.

The collet pad assembly shown in Figures 23, 24. 2S and 26 is composed of segments 55, 56 and 57 which are normally held in assembled condition by means of the rings 43. It will be noted that segments 55, 56 and 57 are tapered at both ends with the taper of the rear portion thereof being adapted to coincide with the taper 2 of sleeve 51. The forward ends of segments 55, 56

the collet chuck nut '54. 58 designates a drill or other tool to be used in the collet.

In the use of the collet pad assembly as shown in'Figures 22 through 26, the collet pad assembly is inserted in the tapered sleeve 51, after which the collet chuck nut 54 is threaded onto the sleeve to retain the collet pad assembly therein. Before the collet chuck nut is tightened, a drill 58 or other tool is inserted in the collet pad assembly, after which the collet chuck nut 54 is tightened onto the collet pad assembly causing the pads 55, 56 and 57 to securely grip the drill or other tool. When it is desired to remove or adjust the drill or other tool, the collet chuck nut is loosened only sufficiently for the pads to release their grip on the drill or other tool, and

with the releasing of the gripping action permitting thev removal of the drill or other tool or to make any neces sary adjustments thereto. v

'It is to be observed, by comparing the collet pads embodying the features of the invention'with the conventional collets, that the subject collet pads are more simple of construction and more economical to manufacture.

After the collet pads are formed, the sameare heat treated in order that suflicient hardness will be embodied therein to prevent excessive wear, rather than the method used in the conventional collets wherein the same must be annealed in order that they may be machined to fit 1. A collet pad assembly adapted to hold a work-piece and to fit into a tapered collet sleeve, said collet pad assembly including a plurality of pads, the pads when assembled contacting each other and having a bore substantially equal to the work-piece passing through the bore, the ends of the collet pads having diameters smaller than the maximum diameter of the pads, the one end of the pads tapering uniformly to snugly fit the taper of the collet sleeve, a pair of grooves near the ends of the collet pads so that the grooves are located in the smaller diameters of the pads, and compression springs mounted in the grooves for biasing the collet pads into contact with the work-piece.

2. A collet pad assembly according to claim 1, wherein each of the collet pads is provided with a radially disposed surface between the larger end of the tapered portion and the other end of the collet pad.

3. A collet pad assembly according to claim 1, wherein both ends of the collet pads are tapered, one end having a much shorter taper than the other end, and wherein the grooves are located in the tapered surfaces in the vicinity of the ends of the collet pads.

4. A collet pad assembly for use in holding a piece, said collet pad assembly being adapted to fit into an internally tapered sleeve, said collet pad assembly including a plurality of pads, the pads when assembled contacting each other and having a bore substantially equal to the piece held in the bare, the ends of the pads having diameters smaller than the maximum diameter of the pads, the one end of the pads tapering uniformly to snugly fit the internal taper of the sleeve, a pair of grooves near the ends of the pads so that the grooves are located in the smaller diameters of the pads, and compression springs mounted in the grooves for biasing the pads into contact with the piece.

5. A collet pad assembly for use in holding a piece, said collet pad assembly being adapted to fit into an internally tapered sleeve, said collet pad assembly into secure by Letters Patent of cluding a plurality of pads, the pads when assembled contacting each other and having a bore substantially equal to the piece held in the bore, the ends of the pads having diameters smaller than the maximum diameter of the pads, the pads tapering uniformly to snugly fit the internal taper of the sleeve, each of the pads being provided with a radially disposed surface between the larger end of the tapered portion and the other end of the pad, a pair of grooves near the ends of the pads so that the grooves are located in the smaller diameters of the pads, and compression springs mounted in the grooves for biasing the pads into contact with the piece.

6. A collet pad assembly for use in holding a piece, said collet pad assembly being adapted to fit into an internally tapered sleeve, said collet pad assembly including a plurality of pads, the pads when assembled contacting each other and having a bore substantially equal to the piece held in the bore, the ends of the pads having diameters smaller than the maximum diameter of the pads, both ends of the pads being tapered, one end having a much shorter taper than the other end, the longer tapered portion tapering uniformly to snugly fit the internally tapered sleeve, a pair of grooves located in the tapered surfaces in the vicinity of the ends of the pads, compression springs mounted in the grooves for biasing the pads into contact with the piece, and a chuck nut threadedly engaging the sleeve, said chuck nut having a taper snugly seated against the shorter taper of the ends of the pads.

7. A collet pad assembly for use in holding a piece, said collet pad assembly being adapted to fit into an internally tapered sleeve, said collet pad assembly ineluding a plurality of pads, the pads when assembled contacting each other and having a bore substantially equal to the piece held in the bore, each end of each of the pads having diameters smaller than the maximum diameter of the pads, each end of each of the pads tapering uniformly to snugly fit the internal taper of the sleeve, a groove at each end of each pad, so that the grooves are located near the ends of the uniformly tapering portions of the pads and so that the grooves are located in the diameters smaller than the maximum diameters of the pads, and compression springs mounted in the grooves for biasing the pads into contact with the piece.

8. A collet pad assembly according to claim 7, wherein the compression springs are flat springs that hold the pads both concentrically and longitudinally with relation to each other.

References Cited in the file of this patent or the original patent UNITED STATES PATENTS 905,919 Pfeifer Dec. 8, 1908 1,044,299 Trundle Nov. 12, 1912 2,040,678 Van Buskirk May 12, 1936 2,374,245 Stoner Apr. 24, 1945 2,601,419 Spahn June 24, 1952 2,697,634 Smith Dec. 21, 1954 FOREIGN PATENTS 182 Great Britain Ian. 3, 1908 566,092 Great Britain Dec. 13, 1944 727,632 Great Britain Apr. 6, 1955 

